Qubits and Pieces

News from the frontline of the weird and wonderful world of quantum computing.

Lucy Sherriff

<p>Lucy Sherriff is a journalist, science geek and general liker of all things techie and clever. In a previous life she put her physics degree to moderately good use by writing about science for that other tech website, The Register. After a bit of a break, it seemed like a good time to start blogging about weird quantum stuff for ZDNet. And so here we are.
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Researchers have known for some time that the quality of graphene produced by vapour deposition depends on a number of factors: the carbon source and the substrate material being major players.However, scientists at the US Department of Energy’s National Laboratory in Oak Ridge have found that hydrogen plays a much more active role in the formation of the material than previously thought.

A quick one to add to the list of fun facts about graphene: if you want to stack it in layers to make a supercapacitor, you’d do well to keep it wet. This fun fact has been brought to our attention by the good people of Monash University in Australia.

Researchers in the Netherlands and Germany have shown that it is possible to send spatially entangled photons down an optical fibre and maintain the entanglement. The trick is to have the right kind of fibre.

University of Bristol researchers, in collaboration with colleagues at the Universities of Osaka and Hokkaido in Japan, have demonstrated a quantum logic gate - a controlled-NOT or CNOT gate - that was first proposed a decade ago.Back in 2001, this four-photon design opened up the possibility of optical quantum computing.

Graphene: famous for being a Nobel Prize prompting wonder material, and for having no band gap. The lack of band gap means graphene’s future as a possible replacement for silicon has always looked bleak, because a band gap is the property that allows a transistor to be switched on and off.

IBM, having wowed us all in April with graphene transistors that run at 155GHz, has gone one step further and now reports success in building a high-speed, graphene-based circuit.The researchers, writing in the June 10 issue of Science, describe how they deposited multiple layers of graphene on a silicon wafer.

This week saw news that Chinese scientists had entangled eight photons, breaking the previous record of six.This is not four entangled pairs, but eight photons that have been sequentially entagled using a non linear crystal.

A flower-like defect in graphene, detailed in a newly published paper, could give scientists more control over the properties of graphene, potentially making sheets of the material more flexible and resistant to tearing.Researchers in the US have described seven defects which could occur naturally in graphene, or under the right conditions, could be induced in the material.

Researchers at Tohoku University on Japan and Delft University of Technology and Science in The Netherlands have experimentally demonstrated “an unprecedented level of control” of pumping electron spins, according to an article published in the 23 May edition of the APS journal Physics Review Letters.

Graphene and its curlier cousin, the carbon nanotube, could revolutionise yet another field, as researchers find that when built into teeny tiny resonators, they have been shown to exhibit non-linear damping.Oh-ho, you say, this could lead to supersensitive devices to detect force or mass.

Using a scanning tunnelling microscope, resolving at a sub-nanometre scale, researchers in the US have taken a detailed look at the edges of graphene nanoribbons (GNR). The researchers aim was to discover how the angle at which the GNR was cut affects the properties of the ribbon’s edges.

Quantum computing research got a major cash injection this week with news that the US Department of defense has sent $14.5million to the UC Santa Barbara, specifically to fund research into spintronics and new nano-scale chips.